Polyanion copolymers for use with conducting polymers in solid electrolytic capacitors

ABSTRACT

A capacitor and a method of making a capacitor, is provided with improved reliability performance. The capacitor comprises an anode; a dielectric on the anode; and a cathode on the dielectric wherein the cathode comprises a conductive polymer and a polyanion wherein the polyanion is a copolymer comprising groups A, B and C represented by Formula A x B y C z  as described herein.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a divisional application of U.S. patentapplication Ser. No. 15/595,137 filed May 15, 2017 which, in turn,claims priority to U.S. Provisional Patent Application No. 62/338,778filed May 19, 2016 both of which is are incorporated herein byreference.

BACKGROUND

The present invention is related to improved polyanions which areparticularly suitable for use with conducting polymers and especially aspart of a cathode of a solid electrolytic capacitor.

Solid electrolytic capacitors are widely used throughout the electronicsindustry. In high voltage applications solid electrolytic capacitorswith a solid electrolyte, formed by conductive polymer dispersions, giveexcellent high voltage performance compared to conductive polymercathodes formed in-situ. These conductive polymer dispersions areprepared by a number of process steps including polymerization,purification, filtration, homogenization, evaporation, etc. Descriptionsof these processes are provided in U.S. Pat. Nos. 5,300,575; 7,990,684;7,270,871; 6,000,840 and 9,030,806; U.S. Patent Publication No.2011/0049433 and PCT Publication WO 2010/089111 each of which isincorporated herein by reference.

Capacitors and methods of making capacitors are provided in U.S. Pat.Nos. 7,990,683; 7,754,276 and 7,563,290 each of which is incorporatedherein by reference.

Solid electrolytic capacitors comprising conducting polymer, as thecathode, have several disadvantages. For example, solid electrolyticcapacitors suffer from poor equivalent series resistance (ESR)particularly under high humidity and high temperature conditions. Inaddition, poor coverage of conducting polymers on corners and edges ofanodized anode results in high DC leakage current. One approach forimproving coverage of the corners and edges is provided in InternationalApplication WO2010089111A1, which is incorporated herein by reference,which describes a group of chemical compounds called crosslinkers orprimer, which are mostly multi-cationic salts or amines. InternationalApplication WO2010089111A1 teaches the application of a solution of thecrosslinker on the anodized anode prior to the application of polymerslurry to achieve good polymer coverage on corners and edges of theanodized anode. The effectiveness of the crosslinker is attributed tothe cross-linking ability of multi-cationic salts or amines to theslurry/dispersion particles. While crosslinkers are advantageous forimproving the coating coverage on corners and edges of the anodizedanode, the addition of these crosslinkers, which are mostly ionic innature, has the unintended consequences of degrading the humidityperformance of a finished product.

Many of the problems associated with solid electrolytic capacitors havenow been found to be the result of the nature of the conductivepolymeric layer and particularly the polyanion counterion of theconductive polymer. The strongly acidic nature of polyanions alsocontributes to increased moisture absorption leading to additionalproblems such as increased corrosion of metals in a capacitive device.The dispersions of conductive polymer and polyanion are also typicallynot effective at forming an adequate coating on the dielectric whichoften leads to thin, or vacant, coatings thereby leading to poor leakagecurrent. Thus, additional binders/additives in conducting polymerdispersions are required to maintain film strength during fabricationand device operation. Moreover, higher the percent solids in conductivepolymer dispersion are desired to improve corner/edge coating coverageof anodized anode and possibly minimize/eliminate use of ioniccross-linker/primer.

It has been found that the use of polyanion copolymer with lowerconcentration of sulfonic acid groups and containing performanceenhancement functional groups such as adhesion promoter/moistureretention/hydrophobic/cross-linkable groups can mitigates the aboveproblems.

The present invention sets forth improvements in the polyanion, methodof making the polyanion and conductive polymer dispersions comprisingthe polyanion.

SUMMARY OF THE INVENTION

It is an object of the invention to provide an improved polyanion whichis particularly suitable for use as a counterion for a conductivepolymer and particularly as a component of a conductive cathode layer ina solid electrolytic capacitor.

It is another object of the invention to reduce sulfonic acidconcentration in a polyanion through the use of copolymer compositioncontaining performance enhancement functional groups.

It is further an object of invention to reduce moisture absorption ofconducting polymer layers.

It is also an object of invention to improve corners/edges coverage ofthe anodized anodes, when forming solid electrolytic capacitors, throughimproved polyanion compositions.

It is also an object of invention to increase the percent solids in aconducting polymer dispersion while retaining viscosity below theprocessible limit.

It is also an object of the invention to provide an improved polyanionwhich is particularly suitable for improving film forming properties ofthe conducting polymer dispersion comprising intrinsically conductingpolymer and polyanion counterion.

These and other advantages, as will be realized, are provided in acapacitor comprising: an anode; a dielectric on the anode; and a cathodeon the dielectric wherein the cathode comprises a conductive polymer anda polyanion wherein the polyanion is a copolymer comprising groups A, Band C represented by Formula A_(x)B_(y)C_(z) as described herein.

Yet another embodiment is provided in a method for forming a capacitorcomprising: forming an anode; forming a dielectric on said anode;forming a cathode on said dielectric wherein said cathode comprises: aconductive polymer; and a polyanion wherein said polyanion is acopolymer comprising groups A, B and C represented by theA_(x)B_(y)C_(z) as described herein.

Yet another embodiment is provided in a slurry comprising a conductivepolymer; and a polyanion wherein said polyanion is a copolymercomprising groups A, B and C represented by the A_(x)B_(y)C_(z) asdescribed herein.

BRIEF DESCRIPTION OF FIGURES

FIG. 1 is a schematic perspective view of a mixing impellor.

FIG. 2 is a schematic perspective view of a high shear impellor.

FIG. 3 is a schematic perspective view of square hole perforated statorscreen.

FIG. 4 is a schematic perspective view of a circular hole perforatedstator screen.

FIG. 5 is a schematic perspective view of a mixer.

FIG. 5A is a schematic perspective bottom view of a portion of FIG. 5.

FIG. 6 is a schematic perspective bottom view of a portion of a mixer.

FIG. 7 is a schematic flow diagram of material in a mixer.

FIG. 8 is a graphical illustrations of advantages of particle size as afunction of RPM.

FIG. 9 is a flow chart representation of dispersion preparation.

FIG. 10 is a schematic representation of conductive polymer dispersionpreparation through inventive “one pot” versus conventional (two step)process.

FIG. 11 is a graphical illustration of viscosity as a function ofpercent solids as in conducting polymer dispersions.

FIG. 12 is a cross-sectional schematic diagram of an embodiment of theinvention.

DESCRIPTION

The present invention is related to improved conductive polymerdispersions and particularly improved polyanions as the counterion ofthe intrinsically conducting polymers and polymer dispersions formedwith the polyanions. More particularly, the present invention is relatedto improved polyanions comprising a copolymer comprising polystyrenesulfonic acid groups, and other functional groups which provide adhesionpromotion, humidity resistance, robust film formation throughinter/intra molecular cross-linking, controlled moisture absorption andother performance improvements. The dispersions comprising improvedpolyanions are particularly suitable for use in the formation of acathode in a solid electrolytic capacitor.

The invention will be described with reference to the various figureswhich are an integral, non-limiting, component of the disclosure.

The inventive polyanion is a, preferably, random copolymer comprisinggroups A, B and C represented by the ratio of Formula A:

-   wherein:-   A is polystyrenesulfonic acid or salt of polystyrenesulfonate;-   B and C separately represent polymerized units substituted with a    group selected from:-   -Carboxyl groups;-   —C(O)OR⁶ wherein R⁶ is selected from the group consisting of:    -   an alkyl of 1 to 20 carbons optionally substituted with a        functional group selected from the group consisting of hydroxyl,        carboxyl, amine, epoxy, silane, amide, imide, thiol, alkene,        alkyne, azide, phosphate, acrylate, anhydride and        -   —(CHR⁷CH₂O)_(b)—R⁸ wherein:        -   R⁷ is selected from a hydrogen or an alkyl of 1 to 7 carbons            and preferably hydrogen or methyl;        -   b is an integer from 1 to the number sufficient to provide a            molecular weight of up to 200,000 for the —CHR⁷CH₂O— group;            and        -   R⁸ is selected from the group consisting of hydrogen,            silane, phosphate, acrylate, an alkyl of 1 to 9 carbons            optionally substituted with a functional group selected from            the group consisting of hydroxyl, carboxyl, amine, epoxy,            silane, amide, imide, thiol, alkene, alkyne, phosphate,            azide, acrylate, and anhydride;-   —C(O)—NHR⁹ wherein:    -   R⁹ is hydrogen or an alkyl of 1 to 20 carbons optionally        substituted with a functional group selected from the group        consisting of hydroxyl, carboxyl, amine, epoxy, silane, amide,        imide, thiol, alkene, alkyne, phosphate, azide, acrylate and        anhydride;-   —C₆H₄—R¹⁰ wherein:    -   R¹⁰ is selected from:    -   a hydrogen or alkyl optionally substituted with a functional        group selected from the group consisting of hydroxyl, carboxyl,        amine, epoxy, silane, amide, imide, thiol, alkene, alkyne,        phosphate, azide, acrylate and anhydride;    -   a reactive group selected from the group consisting of hydroxyl,        carboxyl, amine, epoxy, silane, imide, amide, thiol, alkene,        alkyne, phosphate, azide, acrylate, anhydride and    -   —(O(CHR¹¹CH₂O)_(d)—R¹² wherein:    -   R¹¹ is a hydrogen or an alkyl of 1 to 7 carbons and preferably        hydrogen or methyl;    -   d is an integer from 1 to the number sufficient to provide a        molecular weight of up to 200,000 for the —CHR¹¹CH₂O— group;    -   R¹² is selected from the group consisting of hydrogen, an alkyl        of 1 to 9 carbons optionally substituted with a functional group        selected from the group consisting of hydroxyl, carboxyl, amine,        epoxy, silane, amide, imide, thiol, alkene, alkyne, phosphate,        azide, acrylate and anhydride;-   —C₆H₄—O—R¹³ wherein:    -   R¹³ is selected from:    -   a hydrogen or an alkyl optionally substituted with a reactive        group selected from the group consisting of hydroxyl, carboxyl,        amine, epoxy, silane, amide, imide, thiol, alkene, alkyne,        azide, acrylate, phosphate and anhydride;    -   a reactive group selected from the group consisting of epoxy,        silane, alkene, alkyne, acrylate, phosphate and    -   —(CHR¹⁴CH₂O)_(e)—R¹⁵ wherein:    -   R¹⁴ is a hydrogen or an alkyl of 1 to 7 carbons and preferably        hydrogen or methyl;    -   e is an integer from 1 to the number sufficient to provide a        molecular weight of up to 200,000 for the —CHR¹⁴CH₂O— group; and    -   R¹⁵ is selected from the group consisting of hydrogen and an        alkyl of 1 to 9 carbons optionally substituted with a functional        group selected from the group consisting of hydroxyl, carboxyl,        amine, epoxy, silane, amide, imide, thiol, alkene, alkyne,        azide, acrylate, phosphate and anhydride;-   x, y and z, taken together are sufficient to form a polyanion with a    molecular weight of at least 100 to no more than 500,000 and y/x is    0.01 to 100; z is 0 to a ratio z/x of no more than 100; more    preferably x represents 50-99%, y represents 1 to 50% and z    represents 0 to 49% of the sum total of x+y+z; even more preferably    x represents 70-90%; y represents 10 to 30% and z represents 0 to    20% of the sum total of x+y+z; and-   with the proviso that C is not same as B and z is not zero when B is    substituted with a group selected from:-   C(O)OR⁶ wherein:    -   R⁶ is H or an alkyl substituted with hydroxyl, epoxy or silane        group,    -   (CHR⁷CH₂O)_(b)—R⁸ wherein:    -   R⁷ is H and Fe is phosphate group;-   —C₆H₄—R¹⁰ wherein:    -   R¹⁰ is hydrogen or an alkyl of 1-30 carbon.

In one embodiment the inventive polyanion functions as a coating aidwith insufficient polystyrene sulfonic acid groups to function as anefficient counterion to the conductive polymer. In this instance it ispreferable that in the inventive polyanion represented by Formula Awherein x represents 1-40%, y represents 60 to 99% and z represents 0 to39% of the sum total of x+y+z; even more preferably x represents 5 to40%; y represents 60 to 95% and z represents 0 to 35% of the sum totalof x+y+z.

Particularly preferred polyanions include:

wherein b, x, y and z are as defined above.

The polyanion copolymers are preferably synthesized by a free radicalpolymerization method. By way of non-limiting example, different ratiosof salt of styrene sulfonic acid, to form component A of Formula A, andthe appropriate monomers for formation of components B and C of FormulaA, are polymerized in the presence of free radical initiator at hightemp (ranges from 25° C. to 150° C.) and under inert atmosphericcondition.

The solvent in which the monomer(s) are to be dissolved is preferablywater. A water-soluble solvent may be used, or a mixture of water and awater-soluble solvent may be used. The water-soluble solvent is notparticularly limited. Examples of the solvent include acetone,tetrahydrofuran, methanol, ethanol, isopropanol, andN-methyl-2-pyrrolidone.

The polymerization initiator is not particularly limited, and may be,for example, a peroxide, or an azo compound. Examples of the peroxideinclude ammonium persulfate, potassium persulfate, hydrogen peroxide,cumene hydroperoxide, and di-t-butylperoxide. Examples of the azocompound include 2,2′-azobis(4-methoxy-2,4-dimethylvaleronitrile),2,2′-azobis(2,4-dimethylvaleronitrile), and 2,2′-azobisisobutyronitrile.The polyanion copolymer can be used directly without furtherpurification in the preparation of conductive polymer dispersion asreferred here “one pot synthesis strategy” as described in FIG. 10.Moreover, the polyanion copolymer can be purified, preferably bydialysis, precipitation, ultrafiltration or ion exchange method prior tothe preparation of conductive polymer dispersion through a conventional“two step synthesis techniques”.

The conductive polymer dispersion can be prepared in accordance withU.S. Pat. No. 9,030,806 which is incorporated herein by reference. Thepreferred polymerization method uses a stator screen which provides auniform droplet size resulting in average polymer particle sizes belowabout 200 nm, more preferably 150 nm and even more preferably belowabout 100 nm.

Conductive polymer dispersions having a lower, and controllable, averageparticle size can be prepared during polymerization, without additionalprocess steps, when the polymerization is carried out using a rotorstator mixing system with perforated screen stators preferably with holediameters below about 6 mm. The dispersion may further comprise at leastone polyanion copolymer.

FIGS. 1 and 2 illustrate mixing impellors which can be used buttypically offer poor control over average particle size of the polymer.FIGS. 3 and 4 illustrate preferred stator screens, 10, with squareholes, 12, and circular holes, 14. The stator screens, 10, arepreferably cylindrical and arranged relative to a paddle impellor in anorientation such that material will be forced through the stator screenthereby imparting shear on the material. The stator screens diameter isselected to provide sufficient tip speed to achieve sufficient shear.Tip Speed is defined as:Tip speed=π×D×Nwherein:π is a known constant which is the ratio of a circle's circumference toits diameter;D is the equivalent diameter of the rotor; andN is the rotation rate of the mixer.

As illustrated in FIG. 8, the larger the hole size the higher therotation rate necessary to achieve adequate shear and average particlesize wherein 3000 rpm represents a shear rate of about 21,800 sec⁻¹;6,000 rpm represents a shear rate of about 43,600 sec⁻¹ and 10,000 rpmrepresents a shear rate of about 72,600 sec⁻¹. FIG. 8 illustrates therelation between average particle size and rotational speed using aSilverson lab mixer L5MA with a rotor diameter of 1.2 inches, statorscreen with large (6 mm), medium (2.4 mm), and small (1.6 mm) holes.

Shear rate is defined herein as the tip speed/rotor stator gap. By wayof example, for a rotor diameter of 3.175 cm (1.25 inches) androtational speed of 6,000 RPM the tip speed is 12.8 m/m in (42ft/minute). With a rotor gap of 0.228 mm (0.009 inches) the shear rateis calculated as 51000 sec⁻¹. The shear rate is preferably at leastabout 10,000 to 800,000 sec^(−l) and more preferably at least 40,000 to75,000 sec⁻¹.

Rotor/stator mixers comprise a rotor turning at high speeds within astationary stator. As the blades rotate, materials are continuouslydrawn into one end of the mixing head and expelled at high velocitythrough the openings of the stator. The resulting hydraulic shearreduces the size of suspended droplets. Inline high shear mixers areused in an inline configuration wherein they behave like a centrifugalpump. The basic single-stage inline high shear mixer consists of afour-blade rotor that turns at high speeds within a stationary stator.Rotor tip speeds between 914 to 1,219 m/min (3,000 to 4,000 ft/min.) aretypical. Rotor/stator mixers are offered with a variety ofinterchangeable stator designs.

The “multi-stage” rotor/stator consists of 2-4 rotor/stator pairs nestedconcentrically, mix material moves outward from the center of themulti-stage unit, and it is subjected to a quick succession of shearingevents. Examples of the multistage rotor/stator mixer are the ultrahighshear rate mixers. The X-Series head from Charles Ross and Sons andexemplified in U.S. Pat. No. 5,632,596, consists of concentric rows ofintermeshing teeth. The droplets enter at the center of the stator andmove outward through radial channels in the rotor/stator teeth. Thecombination of extremely close tolerances and very high tip speeds,3,444 m/min (11,300 fpm) or higher, subjects the droplets to intenseshear in every pass through the rotor/stator. The gap between adjacentsurfaces of the rotor and stator are adjustable from 0.254 to 4.57 mm(0.010″ to 0.180″) for very high shear rates such as 750,000 sec⁻¹.

The MegaShear head, exemplified in U.S. Pat. No. 6,241,472, is capableof the highest peak shear and throughput levels. It consists of parallelsemi-cylindrical grooves in the rotor and stator towards which productis forced by high velocity pumping vanes. Different streams are inducedwithin the grooves which collide at high frequency before exiting themix chamber.

Such high shear batch, inline, single stage, and multistage rotor-statormixers are available from various vendors including Charles Ross & sons,Silverson, etc.

The creation of small particle sizes during polymerization is believedto involve the generation of small droplets of monomer through acombination of mechanical energy using a rotor-stator mixing system tomanipulate the droplet size with an appropriate choice of perforatedstator screens, with specific holes having specific equivalentdiameters. It is preferable to stabilize the resulting droplets withsurfactant. In conventional polymerization the monomer droplets arelarge which limits the particle size of the polymer. A mixing system inwhich the mixer produces intense hydraulic shear wherein the monomerdroplets are forced through perforations in the stator screen reducesthe monomer droplets into very small droplet sizes. The very smallmonomer droplets are stabilized by polyanions and the polymerization isbelieved to be initiated around the monomer droplet wherein the dropletsize during polymerization is correlated to the polymer particle size.

Though not limited thereto, the present invention is particularlysuitable for use in forming conductive polymers of polyanilines,polypyrroles and polythiophenes each of which may be substituted. Thepreferred monomer for polymerization is described in Formula 1:

wherein:R¹ and R² independently represent linear or branched C₁-C₁₆ alkyl orC₂-C₁₈ alkoxyalkyl; or are C₃-C₈ cycloalkyl, phenyl or benzyl which areunsubstituted or substituted by C₁-C₆ alkyl, C₁-C₆ alkoxy, halogen orOR³; or R¹ and R², taken together, are linear C₁-C₆ alkylene which isunsubstituted or substituted by C₁-C₆ alkyl, C₁-C₆ alkoxy, halogen,C₃-C₈ cycloalkyl, phenyl, benzyl, C₁-C₄ alkylphenyl, C₁-C₄ alkoxyphenyl,halophenyl, C₁-C₄ alkylbenzyl, C₁-C₄ alkoxybenzyl or halobenzyl, 5-, 6-,or 7-membered heterocyclic structure containing two oxygen elements. R³preferably represents hydrogen, linear or branched C₁-C₁₆ alkyl orC₂-C₁₈ alkoxyalkyl; or are C₃-C₈ cycloalkyl, phenyl or benzyl which areunsubstituted or substituted by C₁-C₆ alkyl;X is S, N or O and most preferable X is S;R¹ and R² of Formula 1 are preferably chosen to prohibit polymerizationat the β-site of the ring as it is most preferred that only α-sitepolymerization be allowed to proceed; it is more preferred that R¹ andR² are not hydrogen and more preferably, R¹ and R² are α-directors withether linkages being preferable over alkyl linkages; it is mostpreferred that the R¹ and R² are small to avoid steric interferences.

In a particularly preferred embodiment the R¹ and R² of Formula I aretaken together to represent —O—(CHR⁴)_(n)—O— wherein:

n is an integer from 1 to 5 and most preferably 2;

R⁴ is independently selected from hydrogen; a linear or branched C₁ toC₁₈ alkyl radical C₅ to C₁₂ cycloalkyl radical, C₆ to C₁₄ aryl radicalC₇ to C₁₈ aralkyl radical or C₁ to C₄ hydroxyalkyl radical, optionallysubstituted with a functional group selected from carboxylic acid,hydroxyl, amine, substituted amines, alkene, acrylate, thiol, alkyne,azide, sulfate, sulfonate, sulfonic acid, imide, amide, epoxy,anhydride, silane, and phosphate; hydroxyl radical; or R⁴ is selectedfrom —(CHR⁵)_(a)—R¹⁶; —O(CHR⁵)_(a)R¹⁶; —CH₂O(CHR⁵)_(a)R¹⁶;—CH₂O(CH₂CHR⁵O)_(a)R¹⁶, orR⁴ is a functional group selected from the group consisting of hydroxyl,carboxyl, amine, epoxy, amide, imide, anhydride, hydroxymethyl, alkene,thiol, alkyne, azide, sulfonic acid, benzene sulfonic acidsulfate, SO₃M,anhydride, silane, acrylate and phosphate;R⁵ is H or alkyl chain of 1 to 5 carbons optionally substituted with afunctional groups selected from carboxylic acid, hydroxyl, amine,alkene, thiol, alkyne, azide, epoxy, acrylate and anhydride;R¹⁶ is H or SO₃M or an alkyl chain of 1 to 5 carbons optionallysubstituted with a functional groups selected from carboxylic acid,hydroxyl, amine, substituted amines, alkene, thiol, alkyne, azide,amide, imide, sulfate, SO₃M, amide, epoxy, anhydride, silane, acrylateand phosphate;a is integer from 0 to 10; andM is a H or cation preferably selected from ammonia, sodium orpotassium.

The conducting polymer is preferably chosen from polypyrroles,polyanilines, polythiophenes and polymers comprising repeating units ofFormula I, particularly in combination with organic sulfonates. Aparticularly preferred polymer is 3,4-polyethylene dioxythiophene(PEDOT).

The polyanion copolymer of Formula A can be used as counterion topoythiophenen comprising repeating units of Formula I. The ratio ofPEDOT to polyanion copolymer in dispersion can be in a range of 1:0.1 to1:10, more preferably 1:1 to 1:5. The a preferred molecular weight ofpolyanion at least about 100 to no more than about 500,000. Below amolecular weight of about 100 film integrity can be affected and above amolecular weight of about 500,000 conductivity and viscosity can beadversely affected.

The viscosity of the polymer dispersion is preferably at least 200 cP@20RPM to no more than 4000 cP@20 RPM at ambient temperature and preferablyat least 600 cP@20 RPM to no more than 2000 cP@20 RPM at ambienttemperature. The dispersion has a preferred percent solids of 1 wt % tono more than 5 wt %. Above about 5 wt % the dispersion does not flowadequately for forming a conductive layer. More preferably, the polymerdispersion has a percent solids of at least 2 wt % to no more than 3.5wt %.

The dispersion, and polymerization preferably occurs at a temperature ofat least about 15° C. to no more than about 35° C. Below a temperatureof about 15° C. the polymerization rate is very slow and above about 35°C. conductivity and viscosity can be adversely affected.

The dispersions comprising intrinsically conductive polymer (ICP) andpolyanion can be further stabilized by polymeric steric stabilizersduring the polymerization. Coagulation or gel formation is significantlyreduced due to the insensitivity of the sterically stabilized system tothe fluctuations and increases in electrolyte concentration. Inaddition, high solids dispersions can be produced by this method due tothe higher stabilizing effect of steric stabilizers.

A criteria for polymeric steric stabilizers for ICP dispersionpolymerization is that they must be stable during low pH polymerizationconditions, stable to oxidizing agents, and that they do not interferewith polymerization of the monomer. An exemplary steric stabilizer is ahigh molecular weight polyethylene oxide and their copolymers which arepreferred as the steric stabilizer due to their stability in low pHreaction conditions. Another exemplary steric stabilizer is polydimethylsiloxane-polyethylene oxide (PDMS-PEO) block copolymer. An advantage ofthe PDMS-PEO copolymer is that the PDMS block could provide moistureresistance in addition to steric stabilization.

Particularly preferred polymeric steric stabilizers comprise linkinggroups which, upon formation of a coated layer, crosslink therebyproviding an interlinked matrix which functions as a binder therebyproviding a coated layer with a suitable structural integrity. Stericstabilizers with a reactive functionality can be employed for postpolymerization crosslinking with the polyanion. Any reactive stericstabilizer with a reactive functionality which is stable during thepolymerization reaction can be used. Examples of such reactivestabilizers are hydroxyl and dihydroxy end capped polybutadiene.Precursors of reactive steric stabilizer can also be employed for postpolymerization activation of the steric stabilizer reactive group.

As used herein, the terminology “steric stabilizer” refers to compoundswhich are adsorbed to the polymer particles of the dispersion andprotective layers around the respective particles to preventagglomeration of the particles.

Suitable steric stabilizers include, for example, protective colloidsand nonionic surfactants having a hydrophilic/lipophilic balance (HLB)greater than about 10. Hydrophilic/lipophilic balance is a measure ofthe degree to which a material is hydrophilic or lipophilic.

For the purposes of the present invention the Griffin's method is usedfor determining the hydrophilic/lipophilic balance wherein HLB isdefined as:HLB=20*Mh/Mwherein:Mh is the molecular mass of the hydrophilic portion of the molecule andM is the molecular mass of the molecule. An HLB value of greater thanabout 10 is a water soluble, lipid insoluble, molecule.

Suitable protective colloids include polyethylene oxide, fullyhydrolyzed polyvinyl alcohol, partially hydrolyzed poly(vinyl alcohol),poly(vinyl pyrollidone), hydroxyethyl cellulose, polyethylene oxidecopolymers and their derivatives, and mixtures thereof. Polyethyleneoxide is preferred. Suitable nonionic surfactants include ethoxylatedalkyl phenols, ethoxylated acetylenic diols, polyethyleneoxide-propylene oxide block copolymers as well as mixtures thereof.Steric stabilizers are preferably added to the polymerization reactionas solutions in water or other polar solvents such as dimethylsulfoxide, ethylene glycol, N-methyl pyrrolidone, etc.

The stator rotor will be described with reference to FIGS. 5 and 6. Amixer, 20, is illustrated in FIGS. 5 and 5A wherein a paddle mixer, 40,is attached to a shaft, 41, coupled to a motor, 42. As illustrated inFIG. 6, which is a perspective bottom view of the stator rotor, thestator screen, 10, encases the paddle mixer. As the paddle mixer rotatesmaterial flows into the interior of the stator screen and is forced outthrough the holes of the stator screen, as depicted in FIG. 7, therebycausing shear which creates small droplets of monomer. The monomer isthen polymerized to form polymer particles with an average particle sizewhich is correlated to the droplet size.

A capacitor of the invention will be described with reference to FIG. 12wherein a capacitor is illustrated in cross-sectional schematic view. InFIG. 12, the capacitor, 1, comprises an anode, 2, with a dielectric, 3,thereon. After completion the conductive polymeric layer is essentiallya continuous preferably un-striated layer, however, it is formed bymultiple process steps and will therefore be described herein with eachlayer discussed separately for the purposes of illustration and clarity.

A first conductive polymer layer, 4¹, is referred to as an internallayer and is formed in a manner sufficient to allow the interstitialareas of the porous dielectric to be adequately coated. The firstconductive layer typically comprises sublayers which are formedsequentially preferably from common components and under commonconditions suitable to coat the interstitial areas of the porousdielectric. The first conductive polymer layer typically comprises 1 to5 layers with each containing a 7 conjugated conductive polymercomprising monomeric unit from Formula 1 as an essential componentthereof. The conducting polymer can be either a water-soluble orwater-dispersible compound. Examples of such a 7 conjugated conductivepolymer include polypyrrole or polythiophene. Particularly preferredconductive polymers include poly(3,4-ethylenedioxythiophene),poly(4-(2,3-dihydrothieno-[3,4-b][1,4]dioxin-2-yl)methoxy)-1-butane-sulphonic acid, salt),poly(4-(2,3-dihydrothieno-[3,4-b][1,4]dioxin-2-yl)methoxy)-1-propane-sulphonic acid, salt),poly(4-(2,3-dihydrothieno-[3,4-b][1,4]dioxin-2-yl)methoxy)-1-methyl-1-propane-sulphonicacid, salt), poly(4-(2,3-dihydrothieno-[3,4-b][1,4]dioxin-2-yl)methoxyalcohol, poly(N-methylpyrrole), poly(3-methylpyrrole),poly(3-octylpyrrole), poly(3-decylpyrrole), poly(3-dodecylpyrrole),poly(3,4-dimethylpyrrole), poly(3,4-dibutylpyrrole),poly(3-carboxypyrrole), poly(3-methyl-4-carboxypyrrole),poly(3-methyl-4-carboxyethylpyrrole),poly(3-methyl-4-carboxybutylpyrrole), poly(3-hydroxypyrrole),poly(3-methoxypyrrole), polythiophene, poly(3-methylthiophene),poly(3-hexylthiophene), poly(3-heptylthiophene), poly(3-octylthiophene),poly(3-decylthiophene), poly(3-dodecylthiophene),poly(3-octadecylthiophene), poly(3-bromothiophene),poly(3,4-dimethylthiophene), poly(3,4-dibutylthiophene),poly(3-hydroxythiophene), poly(3-methoxythiophene),poly(3-ethoxythiophene), poly(3-butoxythiophene),poly(3-hexyloxythiophene), poly(3-heptyloxythiophene),poly(3-octyloxythiophene), poly(3-decyloxythiophene),poly(3-dodecyloxythiophene), poly(3-octadecyloxythiophene),poly(3,4-dihydroxythiophene), poly(3,4-dimethoxythiophene),poly(3,4-ethylenedioxythiophene), poly(3,4-propylenedioxythiophene),poly(3,4-butenedioxythiophene), poly(3-carboxythiophene),poly(3-methyl-4-carboxythiophene),poly(3-methyl-4-carboxyethylthiophene),poly(3-methyl-4-carboxybutylthiophene), polyaniline,poly(2-methylaniline), poly(3 isobutylaniline), poly(2-anilinesulfonate), poly(3-aniline sulfonate), and the like.

Among them, (co)polymers composed of one or two kind(s) selected fromthe group consisting of polypyrrole, polythiophene,poly(4-(2,3-dihydrothieno-[3,4-b][1,4]dioxin-2-yl)methoxy)-1-butane-sulphonicacid, salt),poly(4-(2,3-dihydrothieno-[3,4-b][1,4]dioxin-2-yl)methoxy)-1-methyl-1-propane-sulphonicacid, salt), poly(N-methylpyrrole), poly(3-methylthiophene),poly(3-methoxythiophene), and poly(3,4-ethylenedioxythiophene) etc.

The first conductive polymer layer can be the same as subsequent layers,however, the first conductive polymer layer is preferably formed by atleast one application of a conductive polymer formed by in-situpolymerization formed from solutions of monomer(s), oxidant anddopant(s) or by at least one application of a conductive polymersolution or dispersion having small average particle sizes therebyallowing for adequate penetration.

The internal polymer layer may further comprises substances such assurface-active substances, for example ionic and/or nonionicsurfactants; adhesion promoters, for example organofunctional silanes orhydrolyzates, phosphates thereof, e.g.3-glycidoxypropyl-trialkoxysilane, 3-aminopropyltriethoxysilane,3-mercaptopropyltrimethoxysilane,3-methacryloyloxy-propyltrimethoxysilane, water solublemonomers/oligomers/polymers containing reactive groups such as acid,alcohol, phenol, amines, epoxy, acrylates etc.

The first conductive layer may further comprises small molecular orpolymeric counterions including inventive polyanion.

Subsequent layers of conductive polymer, 4²-4^(n) wherein n is up toabout 10, are referred to collectively as external layers typicallyapplied in the form of a dispersion or solution, wherein the conductivepolymer containing dispersion or solution used to form each layer may bethe same or different thereby resulting in layers which arecompositionally the same or different with a preference for commonalityfor manufacturing convenience. At least one external layer comprises theinventive polyanion as counterion of conductive polymer and preferablyeach of the external layers comprises the inventive polyanion.

The external layers may also independently comprise further substancessuch as surface-active substances, for example ionic and/or nonionicsurfactants; adhesion promoters, for example organofunctional silanes orhydrolyzates, phosphates thereof, e.g.3-glycidoxypropyl-trialkoxysilane, 3-aminopropyltriethoxysilane,3-mercaptopropyltrimethoxysilane,3-methacryloyloxy-propyltrimethoxysilane, vinyltrimethoxysilane oroctyltriethoxysilane, polyurethanes, polyacrylates or polyolefindispersions, or further additives.

The external layers may further independently comprise additives whichenhance the conductivity, for example compounds containing ether groups,for example tetrahydrofuran; compounds containing lactone groups, suchas γ-butyrolactone, rvalerolactone; compounds containing amide or lactamgroups, such as caprolactam, N-methylcaprolactam, N,N-dimethylacetamide,N-methyl-acetamide, N,N-dimethylformamide (DMF), N-methyl-formamide,N-methylformanilide, N-methylpyrrolidone (NMP), N-octylpyrrolidone,pyrrolidone; sulfones and sulfoxides, for examplesulfolane(tetramethylenesulfone), dimethyl sulfoxide (DMSO); sugars orsugar derivatives, for example sucrose, glucose, fructose, lactose,sugar alcohols, for example sorbitol, mannitol; imides, for examplesuccinimide or maleimide; furan derivatives, for example2-furancarboxylic acid, 3-furancarboxylic acid, and/or di- orpolyalcohols, for example ethylene glycol, glycerol or di- ortriethylene glycol. Preference is given to using, asconductivity-enhancing additives, ethylene glycol, dimethyl sulfoxide,glycerol or sorbitol.

The conductive polymer solution or dispersion preferably comprisesreactive monomers as film formers which can improve polymer filmstrength upon drying of the film. The reactive monomer or oligomers canbe soluble in water or organic solvent or disperse in water through theuse of ionic/non-ionic surfactant. The reactive monomers can haveaverage functionalities of at least two or more. The curing process ofthe monomer can be catalyzed by using heat, radiation or chemicalcatalysis. Examples of monomers such as compounds having more than oneepoxy group includes ethylene glycol diglycidyl ether (EGDGE), propyleneglycol diglycidyl ether (PGDGE), 1,4-butanediol diglycidyl ether(BDDGE), pentylene glycol diglycidyl ether, hexylene glycol diglycidylether, cyclohexane dimethanol diglycidyl ether, resorcinol glycidylether, glycerol diglycidyl ether (GDGE), glycerol polyglycidyl ethers,diglycerol polyglycidyl ethers, trimethylolpropane polyglycidyl ethers,sorbitol diglycidyl ether (Sorbitol-DGE), sorbitol polyglycidyl ethers,polyethylene glycol diglycidyl ether (PEGDGE), polypropylene glycoldiglycidyl ether, polytetramethylene glycol diglycidyl ether,di(2,3-epoxypropyl) ether, 1,3-butadiene diepoxide, 1,5-hexadienediepoxide, 1,2,7,8-diepoxyoctane, 1,2,5,6-diepoxycyclooctane, 4-vinylcyclohexane diepoxide, bisphenol A diglycidyl ether, maleimide-epoxycompounds, diglycidyl ether, glycidyl acrylate, glycidyl methacrylate,waterborne dispersion of epoxy resins such as bisphenol A epoxy resin,epoxidized Bisphenol A novolac modified epoxy resin, urethane modifiedBisphenol A epoxy resin, an epoxidized o-cresylic novolac resin and soforth.

Examples of other film formers are monomers containing acidic groups,i.e. oxalic acid, malonic acid, succinic acid, glutaric acid, adipicacid, pimelic acid, suberic acid, azelaic acid, sebacic acid,dodecanedioic acid, phthalic acids, maleic acid, muconic acid, citricacid, trimesic acid, polyacrylic acid, etc. Particularly preferredorganic acids are aromatic acid such as phthalic acid, and particularlyortho-phthalic acid.

Examples of film forming monomers containing alcohol/acrylate groups,such as, diethylene glycol, pentaerythritol, triethylene glycol,oligo/polyethylene glycol, triethylene glycol monochlorohydrin,diethylene glycol monochlorohydrin, oligo ethylene glycolmonochlorohydrin, triethylene glycol monobromohydrin, diethylene glycolmonobromohydrin, oligo ethylene glycol monobromohydrin, polyethyleneglycol, polyether, polyethylene oxide, triethylene glycol-dimethylether,tetraethylene glycol-dimethylether, diethylene glycol-dimethylether,diethylene glycol-diethylether-diethylene glycol-dibutylether,dipropylene glycol, tripropylene glycol, polypropylene glycol,polypropylene dioxide, polyoxyethylene alkylether, polyoxyethyleneglycerin fatty acid ester, polyoxyethylene fatty acid amide,2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, n-butoxyethylmethacrylate, n-butoxyethylene glycol methacrylate, methoxytriethyleneglycol methacrylate, methoxypolyethylene glycol methacrylate,2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, n-butoxyethylacrylate, n-butoxyethylene glycol acrylate, methoxytriethylene glycolacrylate, methoxypolyethylene glycol acrylate, and the like;bifunctional (meth)acrylate compounds, such as, ethylene glycoldi(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene glycoldi(meth)acrylate, polyethylene glycol di(meth)acrylate, neopentyl glycoldi(meth)acrylate, glycerin di(meth)acrylate, and the like; glycidylethers, such as, ethylene glycol diglycidyl ether, glycidyl ether,diethylene glycol diglycidyl ether, triethylene glycol diglycidyl ether,polyethylene glycol diglycidyl ether, propylene glycidyl ether,tripropylene glycidyl ether, polypropylene glycidyl ether, glycerindiglycidyl ether, and the like; glycidyl methacrylate,trimethylolpropane triacrylate, ethylene oxide-modifiedtrimethylolpropane triacrylate, ethylene oxide-modified pentaerythritoltriacrylate, ethylene oxide-modified pentaerythritol tetraacrylate, andthe like.

The external layers may also independently comprise film formingpolyanions containing reactive groups such as epoxy, alcohol, silanes,phosphates, amine, alkene, thiol, alkyne, azide carboxylic acid.

The external layers may also independently comprise, as film formers,linear hyperbranched polymers disclosed in U.S. Pat. No. 9,378,898. Theexternal layer comprising a linear-hyperbranched polymer where thelinear block has at least two reactive end functional groups selectedfrom hydroxyl groups, amino groups, epoxy, acrylate, acid etc. and wherethe hyper-branched block comprises polyether-epoxy, polyester-epoxy,polyester-silanol, polyester-acid, polyether-alcohol, polyamide-acid,polyether-acrylate, polyether-silanol and polyester-amine pendantgroups.

The external layers may further independently comprise work functionmodifiers disclosed in U.S. Publ. No. 20150348715 A1. Example of workfunction modifiers such as organotitanates derivatives selected from thegroup consisting of di-alkoxyacyl titanate, tri-alkoxy acyl titanate,alkoxy triacyl titantate, alkoxy titantate, neoalkoxy titanate, titaniumIV 2,2(bis 2-propenolatomethyl)butanolato, tris neodecanoato-O; titaniumIV 2,2(bis 2-propenolatomethyl)butanolato,iris(dodecyl)benzenesulfonato-O; titanium IV 2,2(bis2-propenolatomethyl)butanolato, tris(dioctyl)phosphato-O; titanium IV2,2(bis 2-propenolatomethyl) tris(dioctyl)pyrophosphatobutanolato-O;titanium IV 2,2(bis 2-propenolatomethyl) butanolato,tris(2-ethylenediamino)ethylato; and titanium IV 2,2(bis2-propenolatomethyl)butanolato, tris(3-amino)phenylato beingrepresentative neoalkoxy titanates and derivatives thereof. Furthermore,work function modifier can be a compounds consisting of cycloaliphaticepoxy resin, ethylene glycol diglycidyl ether, bisphenol A epoxy resin,bisphenol F epoxy resin, bisphenol S epoxy resin, novolac epoxy resin,aliphatic epoxy resin, Glycidylamine epoxy resin, ethylene glycoldiglycidyl ether (EGDGE), propylene glycol diglycidyl ether (PGDGE),1,4-butanediol diglycidyl ether (BDDGE), pentylene glycol diglycidylether, hexylene glycol diglycidyl ether, cyclohexane dimethanoldiglycidyl ether, resorcinol glycidyl ether, glycerol diglycidyl ether(GDGE), glycerol polyglycidyl ethers, diglycerol polyglycidyl ethers,trimethylolpropane polyglycidyl ethers, sorbitol diglycidyl ether(Sorbitol-DGE), sorbitol polyglycidyl ethers, polyethylene glycoldiglycidyl ether (PEGDGE), polypropylene glycol diglycidyl ether,polytetramethylene glycol diglycidyl ether, di(2,3-epoxypropyl)ether,1,3-butadiene diepoxide, 1,5-hexadiene diepoxide, 1,2,7,8-diepoxyoctane,1,2,5,6-diepoxycyclooctane, 4-vinyl cyclohexene diepoxide, bisphenol Adiglycidyl ether, maleimide-epoxy compounds, and derivatives thereof.

External layers may further independently comprise nonionic polymer suchas a hydroxy-functional nonionic polymer. The term “hydroxy-functional”generally means that the compound contains at least one hydroxylfunctional group. The molecular weight of the hydroxy-functional polymermay be from about 100 to 10,000 grams per mole, in some embodiments fromabout 200 to 2,000, in some embodiments from about 300 to about 1,200,and in some embodiments, from about 400 to about 800.

Any of a variety of hydroxy-functional nonionic polymers may generallybe employed. In one embodiment, for example, the hydroxy-functionalpolymer is a polyalkylene ether. Polyalkylene ethers may includepolyalkylene glycols (e.g., polyethylene glycols, polypropylene glycolspolytetramethylene glycols, polyepichlorohydrins, etc.), polyoxetanes,polyphenylene ethers, polyether ketones, and so forth. Polyalkyleneethers are typically predominantly linear, nonionic polymers withterminal hydroxy groups. Particularly suitable are polyethylene glycols,polypropylene glycols and polytetramethylene glycols(polytetrahydrofurans). The diol component may be selected, inparticular, from saturated or unsaturated, branched or unbranched,aliphatic dihydroxy compounds containing 5 to 36 carbon atoms oraromatic dihydroxy compounds, such as, for example, pentane-1,5-diol,hexane-1,6-diol, neopentyl glycol, bis-(hydroxymethyl)-cyclohexanes,bisphenol A, dimer diols, hydrogenated dimer dials or even mixtures ofthe diols mentioned.

In addition to those noted above, other hydroxy-functional nonionicpolymers may also be employed. Some examples of such polymers include,for instance, ethoxylated alkylphenols; ethoxylated or propoxylatedC₆-C₂₄ fatty alcohols; polyoxyethylene glycol alkyl ethers having thegeneral formula: CH₃—(CH₂)₁₀₋₁₆—(O—C₂H₄)₁₋₂₅—OH (e.g., octaethyleneglycol monododecyl ether and pentaethylene glycol monododecyl ether);polyoxypropylene glycol alkyl ethers having the general formula:CH₃(CH₂)₁₀₋₁₆—(O—C₃H₆)₁₋₂₅—OH; polyoxyethylene glycol octylphenol ethershaving the following general formula: C₈—H₁₇—(C₆H₄)—(O—C₂H₄)₁₋₂₅—OH(e.g., Triton™ X-100); polyoxyethylene glycol alkylphenol ethers havingthe following general formula: C₉—H₁₉—(C₆H₄)—(O—C₂H₄)₁₋₂₅—OH (e.g.,nonoxynol-9); polyoxyethylene glycol esters of C₈-C₂₄ fatty acids, suchas polyoxyethylene glycol sorbitan alkyl esters (e.g., polyoxyethylene(20) sorbitan monolaurate, polyoxyethylene (20) sorbitan monopalmitate,polyoxyethylene (20) sorbitan monostearate, polyoxyethylene (20)sorbitan monooleate, PEG-20 methyl glucose distearate, PEG-20 methylglucose sesquistearate, PEG-80 castor oil, and PEG-20 castor oil, PEG-3castor oil, PEG 600 dioleate, and PEG 400 dioleate) and polyoxyethyleneglycerol alkyl esters (e.g., polyoxyethylene-23 glycerol laurate andpolyoxyethylene-20 glycerol stearate); polyoxyethylene glycol ethers ofC₈-C₂₄ fatty acids (e.g., polyoxyethylene-10 cetyl ether,polyoxyethylene-10 stearyl ether, polyoxyethylene-20 cetyl ether,polyoxyethylene-10 oleyl ether, polyoxyethylene-20 oleyl ether,polyoxyethylene-20 isohexadecyl ether, polyoxyethylene-15 tridecylether, and polyoxyethylene-6 tridecyl ether); block copolymers ofpolyethylene glycol and so forth.

The conductive polymer solution or dispersion may have a pH of 1 to 14,preference being given to a pH of 1 to 10, particularly preferred is apH of 1 to 8 with the pH being measured at 25° C. To adjust the pH,bases or acids, for example, can be added to the solutions ordispersions. The bases used may be inorganic bases, for example sodiumhydroxide, potassium hydroxide, calcium hydroxide or ammonia, or organicbases, for example ethylamine, diethylamine, triethylamine, propylamine,dipropylamine, tripropylamine, isopropylamine, diisopropylamine,butylamine, dibutylamine, tributylamine, isobutylamine, diisobutylamine,triisobutylamine, methylpropylamine, methylethylamine,bis(1-methyl)propylamine, 1,1-dimethylethylamine, pentylamine,dipentylamine, tripentylamine, 2-pentylamine, 3-pentylamine,2-methyl-butylamine, 3-methylbutylamine, bis(3-methyl-butylamine),tris(3-methylbutylamine), hexylamine, octylamine, 2-ethylhexylamine,decylamine, N-methyl-butylamine, N-ethylbutylamine,N,N-dimethylethylamine, N,N-dimethylpropyl, N-ethyldiisopropylamine,allylamine, diallylamine, ethanolamine, diethanolamine, triethanolamine,methylethanolamine, methyl-diethanolamine, dimethylethanolamine,diethyl-ethanolamine, N-butylethanolamine, N-butyldiethanol-amine,dibutylethanolamine cyclohexylethanolamine, cyclohexyldiethanolamine,N-ethylethanolamine, N-propylethanolamine, tert-butylethanolamine,tert-butyl-diethanolamine, propanolamine, dipropanolamine,tripropanolamine or benzylamine, bi-, tri-, or tetra-functional amines.The acids used may be inorganic acids, for example sulfuric acid,phosphoric acid or nitric acid, or organic acids, for example carboxylicor sulfonic acids.

It is well known that attaching a lead to a conductive polymer layer isdifficult and it is therefore standard in the art to apply an attachmentlayer, 5, typically comprising layers containing conductive carbon onthe conductive polymer layer and silver containing layers on the carboncontaining layer. A cathode lead, 7, is attached to the attachment layerby a conductive adhesive. An anode lead, 6, is attached to a lead wire,8, typically by welding and the entire assembly, except for portions ofthe cathode lead and anode lead, are encapsulated in a non-conductivematerial, 9, such as a resin.

The process for forming a capacitor will be described with reference toFIG. 9 wherein the process is represented schematically. In FIG. 9, adroplet of monomer is formed at 100 preferably by a stator rotor asdefined herein. The droplets are then polymerized preferably in thepresence of inventive polyanion formed by the one pot or two stepprocess detailed further herein to form a polymer at 102. An anode isprepared at 104 wherein the anode is a conductor, and preferably a valvemetal. A dielectric is formed on the anode at 106 wherein the preferreddielectric is an oxide of the anode. A conductive layer of the polymeris formed on the dielectric at 108 thereby forming a conductive couplewith a dielectric there between. The capacitor is finished at 110wherein finishing can include but is not limited to testing, formingexternal terminations, encapsulating and the like.

The anode material is not limited herein. A particularly preferred anodematerial is a metal and a particularly preferred metal is a valve metalor a conductive oxide of a valve metal. Particularly preferred anodesinclude niobium, aluminum, tantalum and NbO without limit thereto.

The dielectric is not particularly limited herein. A particularlypreferred dielectric is an oxide of the anode due to manufacturingconsiderations.

Throughout the description the term “equivalent hole diameter” or“equivalent diameter” refers to a hole wherein the cross-sectional areais the same as that of a circle with the stated diameter.

Throughout the description terms such as “alkyl”, “aryl”, “alkylaryl”,“arylalkyl” refer to unsubstituted or substituted groups and if alreadylisted as substituted, such as “alkyl alcohol” refer to groups which arenot further substituted or may be further substituted.

Test Methods

Determination of % PSSA in Polyanion Copolymer

NMR spectroscopy analysis was used to determine the % PSSA in copolymer;to this end, the peaks at 6.0 to 8.0 ppm correspond to aromatic protonof PSSA and 1.0 to 4.0 ppm (aliphatic proton of copolymer backbone) areconsidered relative to one another. This gives rise to a ratio ofstyrene units to acrylate units in the copolymer, which relativelycorrespond to a % PSSA in polyanion copolymer.

Determination of the Water Absorption Property of Conducting PolymerDispersion

The conductive polymer film was prepared by dip coating the conductivedispersion on to a glass slide and drying at 150° C. for 30 min. Theweight of dry film was recorded. Then, the conductive polymer film wasimmersed in water for 5 min. The weight of wet film was recordedimmediately after gently wiping off residual water on the film. Theamount of water absorption was calculated as the difference between wetfilm and dry film and scaled as shown below: +=<5% water absorption,++=5-30% water absorption, +++=>30% water absorption

Corners and Edge Coverage Measurement

Corner and edge coverage of conducting polymer dispersions on ananodized anode in capacitors was inspected under a microscope and scaledper the following criteria: Edges Not Covered 85%, Corners Not Covered90%, Half of Corners Covered 95% Corners Appear Completely Covered 99%

Peeling Test in Hot Water

The conductive polymer film was prepared by dip coating the conductivedispersion on a glass slide and drying at 150° C. for 30 min. On thesurface of the coating, an incision was made in a reticular patternusing a cutter knife so that the incision reached the glass substrate.The film was then immersed in hot water for 15 min. On the surface ofthe coating having an incision, a cellophane tape was attached, and thenpeeled. The peeling situation of the film on glass substrate wasvisually observed and recorded.

EXAMPLES

In the examples which follow the conductive polymer waspoly(3,4-ethylenedioxythiophene) in all cases for consistency.

Synthesis of Polyanion Copolymer Example 1 Synthesis ofpoly(4-styrenesulfonic acid-co-hydroxy ethyl acrylate) sodium salt

Under an argon atmosphere, a 500 ml flask was initially charged with 33ml deionized water as a solvent. After adding 8 g styrenesulfonic acidsodium salt, 2 g hydroxyl ethyl acrylate and 1 gm ammonium persulfate,the mixture was saturated with nitrogen by means of a gas inlet tube. Tothis end, nitrogen was passed through the mixture for 15 min. Duringthis time, the mixture was heated to 70° C. The flask was sealed with arubber septum and the solution was polymerized for 2 hours. Theresulting polyanion copolymer was acidified with dilute sulfuric acidand used directly for preparation of conducting polymer dispersion.

The polyanion copolymer was characterized for % polystyrene sulfonicacid (PSSA) content in polyanion copolymer by ¹H NMR and summarized inTable 1.

Example 2 Synthesis of poly(4-styrenesulfonic acid-co-acrylamide) sodiumsalt

The polyanion was synthesized using the same procedure as in Example 1except 8 g styrenesulfonic acid sodium salt, and 2 g acrylamide was usedas monomers.

Example 3

The polyanion was synthesized using the same procedure as in Example 2except the resulting polymer was purified by dialysis in water for 24hours.

The polyanion copolymer was characterized for % polystyrene sulfonicacid (PSSA) content in polyanion copolymer by ¹H NMR and summarized inTable 1.

Example 4 Synthesis of poly(4-styrenesulfonic acid-co-Poly(ethyleneglycol) methacrylate) sodium salt

The polyanion was synthesized using the same procedure as mentioned inExample 1 except 5 g styrenesulfonic acid sodium salt, and 5 gpoly(ethylene glycol) methacrylate was used as monomers.

Example 5

The polyanion was synthesized using the same procedure as mentioned inExample 2 except the polymer was purified by dialysis in water for 24hours.

Example 6

The polyanion was synthesized using the same procedure as mentioned inExample 1 except 8 g styrenesulfonic acid sodium salt, and 2 gpoly(ethylene glycol) methacrylate was used as monomers.

Example 7 Synthesis of poly(4-styrenesulfonic acid-co-Poly(ethyleneglycol) methacrylate-co-glycidyl acrylate) sodium salt dispersion

The polyanion dispersion was synthesized using the same procedure asmentioned in Example 1 except 5 g styrenesulfonic acid sodium salt, 5 gpoly(ethylene glycol) methacrylate and 10 gm glycidyl acrylate were usedas monomers and high shear mixing was used to form dispersion.

The polyanion copolymer was characterized for % polystyrene sulfonicacid (PSSA) content in polyanion copolymer by ¹H NMR and summarized inTable 1.

TABLE 1 PSSA CONTENT IN POLYANION COPOLYMER Sample % PSSA in copolymerExample 1 89% Example 3 66% Example 5 45% Control 100% 

Preparation of Conducting Polymer Dispersion Comparison Example 1

2531 g of DI water and 125 g of PSSA 30% (Alfa Aesar) were charged intoa 4 L polyethylene bottle. The reaction solution was purged withnitrogen for 0.5-1 hr. The contents were mixed using a rotor-statormixing system with perforated stator screen with a round hole diameterof 0.6 mm. Subsequently, 28.5 g of 0.1% ferric sulfate solution and 21.5g of sodium persulfate were then added into the reaction mixture,followed by dropwise addition of 11.25 g of 3,4-ethylenedioxythiophene(EDOT) (Baytron M from Heraeus). The reaction mixture was shearedcontinuously with a shear speed at 6,000 rpm for 24 hours. 300 g ofLewatit S108H and 300 g of Lewatit MP62WS ion exchange resins were addedinto the slurry and rolled at around 60 rpm overnight. The conductivepolymer dispersion was separated from resins by filtration.

Example 8

A conducting polymer dispersion was prepared in the same manner as inComparison Example 1 except polyanion from Example 1 was used.

Example 9

A conducting polymer dispersion was prepared in the same manner asComparison Example 1 except the polyanion from Example 2 was used.

Example 10

A conducting polymer dispersion was prepared in the same manner asComparison Example 1 except the polyanion from Example 3 was used.

Example 11

A conducting polymer dispersion was prepared in the same manner asComparison Example 1 except the polyanion from Example 4 was used.

Example 12

A conducting polymer dispersion was prepared in the same manner asComparison Example 1 except the polyanion from Example 5 was used.

Example 13

A conducting polymer dispersion was prepared in the same manner asComparison Example 1 except the polyanion from Example 6 was used andthe deionized water (DI water) quantity was adjusted to achieve thedesired % solids. The improved polyanion copolymer resulted in high %solids in conducting polymer dispersion at relatively ower viscositycompare to prior-art polyanion as illustrated in FIG. 11.

The water absorption properties of conducting polymer dispersionprepared using polyanion copolymer was measured. As shown in Table 2,the conducting polymer dispersion comprising polyanion copolymer showedvarying degrees of water absorption which could be due to differences intheir structural composition.

TABLE 2 WATER ABSORPTION PROPERTIES OF INVENTIVE CONDUCTING POLYMERDISPERSIONS Sample Water absorption Example 8 + Example 10 +++ Example12 + Comparision example 1 ++

Conductive Polymer Dispersion Formulation for Coating on SolidElectrolytic Capacitor Comparison Example 2

Conducting polymer dispersions from Comparison Example 1 were mixed withDMSO, 3-glycidoxypropyltrimethoxysilane and reactive monomers containingtwo epoxy and two carboxylic groups followed by mixing on rollerovernight.

Example 14

The coating formulation was prepared in the same manner as Example 2except the conducting polymer dispersion from Example 8 was used.

Example 15

The coating formulation was prepared in the same manner as ComparisonExample 2 except the conducting polymer dispersion from Example 9 wasused.

Example 16

The coating formulation was prepared in the same manner as ComparisonExample 2 except the conducting polymer dispersion from Example 10 wasused.

Example 17

The coating formulation was prepared in the same manner as ComparisonExample 2 except the conducting polymer dispersion from Example 11 wasused.

Example 18

The coating formulation was prepared in the same manner as comparisonExample 2 except the conducting polymer dispersion from Example 12 wasused.

Example 19

The coating formulation was prepared in the same manner as comparisonExample 2 except the conducting polymer dispersion from Example 13 andwaterborne dispersion of reactive monomer/oligomer containing at leastthree epoxy groups was used.

Example 20

Conducting polymer dispersion from Comparative Example 1 was mixed withDMSO, 3-glycidoxypropyltrimethoxysilane, polyanion copolymer dispersionfrom Example 7 followed by mixing on a roller overnight.

Example 21

The coating formulation was prepared in the same manner as Example 19except polyanion copolymer dispersion from Example 7 was addedadditionally into the mixture.

Fabrication of Solid Electrolytic Capacitors Comparison Example 3

A series of tantalum anodes (68 microfarads, 16V) were prepared. Thetantalum was anodized to form a dielectric on the tantalum anode. Theanodes thus formed was dipped into a solution of iron (III)toluenesulfonate oxidant for 1 minute and sequentially dipped intoethyldioxythiophene monomer for 1 minute to form an anodized anode. Theanodized anodes were washed to remove excess monomer and by-products ofthe reactions after the completion of 60 minutes of polymerization,thereby forming a thin layer of conductive polymer (PEDOT) on thedielectric of the anodized anodes. This process was repeated until asufficient thickness was achieved. Conductive polymer dispersion fromComparison Example 2 was applied to form an external polymer layer.After drying, alternating layers of a commercial crosslinker solution,Clevios® K Primer, and conductive polymer dispersion from ComparisonExample 2 were applied and repeated 4 times, parts were inspected undermicroscope for corners and edge coverage. A sequential coating of agraphite layer and a silver layer were applied to produce a solidelectrolytic capacitor. Parts were assembled and packaged.

Example 22

A series of tantalum anodes were prepared and tested in a similarfashion as in Comparison Example 3, except that conductive polymerdispersion from Example 14 was applied to form an external polymerlayer.

Example 23

A series of tantalum anodes were prepared and tested in a similarfashion as in Comparison Example 3, except that conductive polymerdispersion from Example 15 was applied to form an external polymerlayer.

Example 24

A series of tantalum anodes were prepared and tested in a similarfashion as in Comparison Example 3, except that conductive polymerdispersion from Example 16 was applied to form an external polymerlayer.

Example 25

A series of tantalum anodes were prepared and tested in a similarfashion as in Comparison Example 3, except that conductive polymerdispersion from Example 17 was applied to form an external polymerlayer.

Example 26

A series of tantalum anodes were prepared and tested in a similarfashion as in Comparison Example 3, except that conductive polymerdispersion from Example 18 was applied to form an external polymerlayer.

Example 27

A series of tantalum anodes were prepared and tested in a similarfashion as in Comparison Example 3, except that conductive polymerdispersion from Example 19 was applied to form an external polymerlayer.

Example 28

A series of tantalum anodes were prepared and tested in a similarfashion as in Comparison Example 26, except that conductive polymerdispersion from Example 19 was applied without use of alternating layersof a commercial crosslinker solution Clevios® K Primer.

Example 29

A series of tantalum anodes were prepared and tested in a similarfashion as in Example 28, except the anode was dipped into a watersoluble conductive polymerpoly(4-(2,3-dihydrothieno-[3,4-b][1,4]dioxin-2-yl)methoxy)-1-butane-sulphonicacid to form internal layer before applying an external polymer layer.

As described in Table 3, the conducting polymer dispersion comprisinginventive polyanion copolymer with adhesion promoter group in Example 27and 28 showed improvement in polymer coverage in solid electrolyticcapacitor. The inventive polyanion also showed excellent ESR stabilityunder 85° C./85% RH load humidity condition.

TABLE 3 ELECTRICAL PERFORMANCE OF INVENTIVE CONDUCTING POLYMERDISPERSION IN SOLID ELECTROLYTIC CAPACITOR ESR (mΩ) after 85° C./85% %coverage ESR RH load humidity test Sample (3^(rd) dip) (mΩ) (1000 hrs.)Example 27 99 35.0 136.8 Example 28 99 38.2 98.4 Comparision 95 32.0264.7 Example 3

Table 4 shows the conductivity measurements of polymer dispersionprepared through inventive one pot synthesis process. It was found thatsignificant improvement in conductivity was obtained by the dialysispurification of polyanion copolymer

TABLE 4 EFFECT OF PURIFICATION BY DIALYSIS OF POLYANION COPOLYMER ONCONDUCTIVITY One pot strategy Two step process Conductivity ConductivitySample (S/cm) Sample (S/cm) Example 15 48.9 Example 16 114.7 Example 177.9 Example 18 66.6

As shown in Table 5, It was surprisingly found that some polyanioncopolymers dispersion prepared through one pot synthesis strategydemonstrates comparable ESR performance even though it has lowerconductivity than dispersion prepared through two step process.

TABLE 5 ELECTRICAL PROPERTIES OF CONDUCTING POLYMER DISPERSIONS PREPAREDBY ONE POT(ONE STEP) AND PRIOR ART TWO STEP METHOD One pot strategy TwoSteps Process Sample ESR (mΩ) Sample ESR (mΩ) Example 22 66.5 Example 2344.5 Example 25 35.6 Example 26 32.0

The inventive polyanion copolymer dispersion was also used as a filmforming additive in conductive polymer dispersion. The polymer film wastested for electrical conductivity and film strength. As shown in Table6, surprisingly the polyanion copolymer dispersion as additive inconducting polymer dispersion does not reduce the electricalconductivity and retains good film strength in hot water.

TABLE 6 CONDUCTIVITY AND FILM FORMING PROPERTY OF CONDUCTING POLYMERDISPERSION Conductive polymer dispersion PEDOT:PSSA PEDOT:PSSAPEDOT:PSSA PEDOT:PSSA Film forming Additive None Prior art prior art nonPolyanion copolymer binder polyanion dispersion additives (Example 7)Conductivity (S/cm) 200 120 100 180 Peeling after hot water Yes Yes NoNo immersion for 15 min?

The invention has been described with reference to preferred embodimentswithout limit thereto. One of skill in the art would realize additionalembodiments and alterations which are not specifically stated but whichare within the scope of the invention as more specifically set forth inthe claims appended hereto.

The invention claimed is:
 1. A slurry comprising: a conductive polymer;and a polyanion wherein said polyanion is a copolymer comprising groupsA, B and C represented the ratio of Formula A:

wherein: A is polystyrenesulfonic acid or salt of polystyrenesulfonate;B and C separately represent polymerized units substituted by a groupselected from: —C(O)OR⁶ wherein R⁶ is selected from the group consistingof: —(CHR¹⁷)_(b)—R¹⁸ wherein: R¹⁷ is selected from a hydrogen or analkyl of 1 to 7 carbons; b is an integer from 1 to 10; and R¹⁸ isselected from the group consisting of phosphate, acrylate, hydroxyl,epoxy, thiol, alkene, alkyne, azide and anhydride; —(CHR⁷CH₂O)_(b)—R⁸wherein: R⁷ is selected from a hydrogen or an alkyl of 1 to 7 carbons; bis an integer from 1 to the number sufficient to provide a molecularweight of up to 200,000 for the —CHR⁷CH₂O— group; and R⁸ is selectedfrom the group consisting of hydrogen, silane, phosphate, acrylate, analkyl of 1 to 9 carbons optionally substituted with a functional groupselected from the group consisting of hydroxyl carboxyl, amine, epoxy,silane, amide, phosphate, imide, thiol, alkene, alkyne, azide, acrylateand anhydride; —C(O)—NHR⁹ wherein: R⁹ is a hydrogen or an alkyl of 1 to20 carbons optionally substituted with a functional group selected fromthe group consisting of hydroxyl, carboxyl, amine, epoxy, silane, amide,phosphate, imide, thiols, alkene, alkyne, azide, acrylate and anhydride;x, y and z, taken together are sufficient to form a polyanion with amolecular weight of at least 100 to no more than 500,000 and y/x is 0.01to 100; z is 0 to a ratio z/x of no more than 100; and with the provisothat C is not same as B and z is not zero when B is substituted with agroup selected from: C₆H₄—R¹⁰ wherein: R¹⁰ is hydrogen or an alkyl of1-30 carbon.
 2. The slurry of claim 1 wherein said copolymer is a randomcopolymer.
 3. The slurry of claim 1 wherein when B or C is—(CHR⁷CH₂)_(b)R⁸, R⁷ is selected from hydrogen and methyl.
 4. The slurryof claim 1 wherein x represents 50-99%, y represents 1-50% and zrepresents 0-49% of the sum total of x+y+z.
 5. The slurry of claim 4where x represents 70-90%; y represents 10-30% and z represents 0-20% ofthe sum total of x+y+z.
 6. The slurry of claim 1 wherein x represents1-40%, y represents 60-99% and z represents 0-39% of the sum total ofx+y+z.
 7. The slurry of claim 6 where x represents 5-40%; y represents60-95% and z represents 0-35% of the sum total of x+y+z.
 8. A slurrycomprising: a conductive polymer; and a polyanion wherein said polyanionis selected from the group consisting of:

wherein each x, y and z, independently taken together for each saidpolyanion, are sufficient to form a polyanion with a molecular weight ofat least 100 to no more than 500,000 and y/x is 0.01 to 100; z is 0 to aratio z/x of no more than 100; and each b is independently an integerfrom 1 to
 10. 9. The slurry of claim 1 wherein said conductive polymeris selected from the group consisting of polyaniline, polypyrrole andpolythiophene.
 10. The slurry of claim 9 wherein said conductive polymercomprises repeating units of Formula 1:

wherein: R¹ and R² independently represent linear or branched C₁-C₁₆alkyl or C₂-C₁₈ alkoxyalkyl; or are C₃-C₈ cycloalkyl, phenyl or benzylwhich are unsubstituted or substituted by C₁-C₆ alkyl, C₁-C₆ alkoxy,halogen or OR₃; or R¹ and R², taken together, are linear C₁-C₆ alkylenewhich is unsubstituted or substituted by C₁-C₆ alkyl, C₁-C₆ alkoxy,halogen, C₃-C₈ cycloalkyl, phenyl, benzyl, C₁-C₄ alkylphenyl, C₁-C₄alkoxyphenyl, halophenyl, C₁-C₄ alkylbenzyl, C₁-C₄ alkoxybenzyl orhalobenzyl, 5-, 6-, or 7-membered heterocyclic structure containing twooxygen elements, R³ preferably represents hydrogen, linear or branchedC₁-C₁₆ alkyl or C₂-C₁₈ alkoxyalkyl; or are C₃-C₈ cycloalkyl, phenyl orbenzyl which are unsubstituted or substituted by C₁-C₆ alkyl; and X isS, N or O.
 11. The slurry of claim 10 wherein X is S.
 12. The slurry ofclaim 10 wherein R¹ and R² are taken together to represent—O—(CHR⁴)_(n)—O— wherein: n is an integer from 1 to 5; R⁴ isindependently selected from hydrogen; a linear or branched C₁ to C₁₈alkyl radical C₅ to C₁₂ cycloalkyl radical, C₆ to C₁₄ aryl radical C₇ toC₁₈ aralkyl radical or C₁ to C₄ hydroxyalkyl radical optionallysubstituted with a functional group selected from carboxylic acid,hydroxyl, amine, substituted amines, alkene, thiol, alkyne, azide,sulfate, sulfonate, sulfonic acid, imide, amide, epoxy, anhydride,silane, and phosphate; hydroxyl radical; or R⁴ is selected from—(CHR⁵)_(a)—R¹⁶; —O(CHR₅)_(a)R¹⁶; —OCH₂(CHR⁵)_(a)R⁶,—OCH₂(CH₂CHR⁵O)_(a)R¹⁶; or R⁴ is a functional group selected from thegroup consisting of hydroxyl, carboxyl, amine, epoxy, amide, imide,anhydride, hydromethyl, carboxylic acid, hydroxymethyl, alkene, thiol,alkyne, azide, sulfate, sulfonic acid, benzene sulfonic acid, SO₃M,anhydride, epoxy, silane, acrylate and phosphate; R⁵ is H or alkyl chainof 1 to 5 carbons optionally substituted with a functional groupsselected from carboxylic acid, hydroxyl; amine, alkene, thiol, alkyne,azide, epoxy, silane; acrylate, anhydride and phosphate; R¹⁶ is H orSO₃M or an alkyl chain of 1 to 5 carbons optionally substituted with afunctional groups selected from carboxylic acid, hydroxyl, amine,substituted amines, alkene, thiol, alkyne, azide, amide, imide, sulfate,SO₃M, amide, epoxy, anhydride, silane, acrylate and phosphate; a is from0 to 10; and M is a H or cation preferably selected from ammonia, sodiumor potassium.
 13. The slurry of claim 12 wherein n is
 2. 14. The slurryof claim 12 wherein said conductive polymer is 3,4-polyethylenedioxythiophene.